查找MongoDB文档，其中数组元素具有特定值？
要匹配MongoDB中的文档，请使用$elemMatch。首先让我们创建一个包含文档的集合-
> db.demo15.insertOne({"Details":[{"Score":56},{"Score":78}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e0f7806d7df943a7cec4fab")
}
> db.demo15.insertOne({"Details":[{"Score":86},{"Score":86}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e0f7817d7df943a7cec4fac")
}
> db.demo15.insertOne({"Details":[{"Score":97},{"Score":85}]});
{
"acknowledged" : true,
"insertedId" : ObjectId("5e0f7823d7df943a7cec4fad")
}以下是在find()方法的帮助下显示集合中所有文档的查询-
> db.demo15.find();
这将产生以下输出-
{ "_id" : ObjectId("5e0f7806d7df943a7cec4fab"), "Details" : [ { "Score" : 56 }, { "Score" : 78 } ] }
{ "_id" : ObjectId("5e0f7817d7df943a7cec4fac"), "Details" : [ { "Score" : 86 }, { "Score" : 86 } ] }
{ "_id" : ObjectId("5e0f7823d7df943a7cec4fad"), "Details" : [ { "Score" : 97 }, { "Score" : 85 } ] }这是查找文档的查询，其中文档中数组的所有元素均具有特定值-
> db.demo15.find({
... "Details.Score" : {
... $exists : true
... },
... "Details" : {
... $not : {
... $elemMatch : {
... "Score" : {
... $ne : 86
... }
... }
... }
... }
... });这将产生以下输出-
{ "_id" : ObjectId("5e0f7817d7df943a7cec4fac"), "Details" : [ { "Score" : 86 }, { "Score" : 86 } ] }